Conformal Coating Surface Preparation Hub
Cleaning, contamination control, adhesion preparation and pre-coating process stability for PCB coating
This hub focuses on preparing PCB assemblies before conformal coating.
Surface preparation is one of the most important stages in any conformal coating process. Cleaning, contamination control, handling discipline and surface condition all influence coating adhesion, wetting, coverage and long-term reliability.
Many coating failures are not caused by the coating material itself. They are often caused by residues, flux contamination, silicone transfer, poor handling, moisture, low surface energy or inconsistent pre-coating control.
This hub brings together SCH technical guidance on preparing PCB assemblies before conformal coating, helping engineers understand where surface preparation fits within the wider coating process.
Simple overview of the conformal coating surface preparation workflow including cleaning, surface activation, handling, verification and coating application.
Where are you in the preparation process?
- Investigating adhesion or wetting problems โ De-Wetting & Poor Wetting
- Reviewing contamination or corrosion risk โ Corrosion & Ionic Contamination
- Considering plasma cleaning or activation โ Plasma Cleaning & Surface Activation
- Building a controlled production process โ Surface Preparation & Process Control
Surface Preparation Index
| Topic | More | Article |
|---|---|---|
| Surface Preparation & Cleanliness โ cleaning, contamination control and coating readiness | ๐ | โ |
| Plasma Cleaning & Surface Activation โ adhesion improvement for difficult surfaces | ๐ | โ |
| De-Wetting โ contamination, poor wetting and low surface energy failures | ๐ | โ |
| Corrosion & Ionic Contamination โ residues and electrochemical reliability risk | ๐ | โ |
| Process Control Link โ how preparation fits into production coating control | ๐ | โ |
Surface Preparation & Cleanliness
Conformal coatings are only as reliable as the surface they are applied to. Even a technically suitable coating can fail if the PCB surface contains residues, contamination or surface conditions that prevent wetting and adhesion.
- Control flux residues, oils, fingerprints, dust and silicone transfer before coating.
- Define what โcleanโ means for the assembly and coating chemistry being used.
- Control handling, storage and time between cleaning and coating.
- Verify that the preparation process supports adhesion, wetting and inspection requirements.
Plasma Cleaning & Surface Activation
Plasma treatment can improve surface energy and adhesion where materials are difficult to coat or where contamination and low-energy surfaces create coating reliability risks.
- Use plasma where cleaning alone may not provide adequate surface activation.
- Validate plasma parameters against the actual substrate, coating and production process.
- Control time between plasma treatment and coating application.
- Use plasma as part of a defined process, not as a universal fix for poor cleanliness.
De-Wetting and Poor Wetting
De-wetting occurs when coating pulls away from the surface instead of forming a stable continuous film. It is often linked to contamination, low surface energy, residues or incompatible materials.
- Check for silicone, oils, flux residues and handling contamination.
- Review cleaning process, surface condition and coating compatibility.
- Separate wetting problems from spray, dip or selective coating setup issues.
- Use inspection evidence to confirm whether the issue is localised or process-wide.
Corrosion & Ionic Contamination
Ionic residues can remain active under a conformal coating and create long-term reliability risks. Coating does not automatically neutralise contamination already present on the assembly.
- Control ionic residues before coating rather than relying on coating to compensate.
- Consider corrosion risk where moisture, voltage bias and contamination may combine.
- Link cleanliness checks to coating qualification and reliability testing.
- Investigate contamination early when field failures or corrosion symptoms appear.
Surface Preparation and Process Control
Surface preparation should be controlled through defined work instructions, inspection checkpoints and process records. It is not enough to specify that boards must be โcleanโ; the production process must define what clean means, how it is achieved and how it is verified.
- Define cleaning method, drying time, handling controls and storage conditions.
- Control maximum time between cleaning, plasma treatment and coating.
- Record pre-coating inspection and process compliance evidence.
- Link surface preparation to coating method, masking strategy and final qualification testing.
How Surface Preparation Links to the Wider Process
Surface preparation is upstream of the application method. Spray coating, dip coating and selective coating all depend on the same basic principle: the coating must be able to wet, bond and remain stable on the prepared surface.
- Conformal Coating Processes Hub โ master process navigation and overview.
- Application Methods Hub โ spray, dip, selective coating and process route selection.
- Defects Hub โ coating failure mechanisms and defect troubleshooting.
- Inspection & Quality Hub โ inspection, verification and coating quality control.
Need Help With Surface Preparation or Adhesion Problems?
SCH Services supports customers with conformal coating process development, cleaning reviews, adhesion investigation, plasma cleaning assessment, coating trials and production troubleshooting.
Why Choose SCH Services?
Partnering with SCH Services means more than just outsourcing โ you gain a complete, integrated platform for Conformal Coating, Parylene & Advanced Functional Coating Solutions, alongside equipment, materials, and training, all backed by decades of hands-on expertise.
- โ๏ธ 25+ Years of Expertise โ Specialists in coating technologies trusted worldwide.
- ๐ ๏ธ End-to-End Support โ Cleaning review, adhesion investigation, surface preparation control, masking strategy and inspection planning.
- ๐ Scalable Solutions โ From prototypes to high-volume production.
- ๐ Global Reach โ Responsive support across Europe, North America, and Asia.
- โ Proven Reliability โ Consistent results across services, equipment, and materials.
๐ Call: +44 (0)1226 249019 | โ Email: sales@schservices.com | ๐ฌ Contact Us โบ
